1. Field of the Invention
This invention relates to evaporators for concentrating liquids to enable a small or trace amount of solute to be identified or processed.
2. Prior Art
Evaporative concentrators commonly used by commercial or testing laboratories have been of the columnar type usually composed of two or more sections including a principal evaporating section and a bottom sample-holding section. Such bottom section includes a concentrate holding lower chamber of a size much smaller in volume than the upper chamber of such lower sample-holding section. A collector and condensing-chimney section may be superimposed on the principal evaporating section.
The sections of the evaporative concentrator apparatus are tubular, preferably of circular cross section, and are usually made of Pyrex glass.
Such apparatus is commonly referred to as a Kuderna-Danish evaporative concentrator, an illustration and description of which are shown in the center unit of FIG. 14-3 on page 231 and described on pages 232 and 233 of the reference book Analysis of Insecticides and Acaricides, by Francis A. Gunther and Roger C. Blinn, Interscience Publishers, Inc., New York, copyright 1955. The description states that the apparatus is available from the Precision Distillation Apparatus Company, Santa Monica, Calif.
On page 232, it is stated that the concentrator is charged with the stripping solution to about the midpoint of the flask, and the unit is supported in a steam or boiling water bath in a good hood in such a way that the lower one-third of the flask is bathed in steam. When the receiver is nearly .-+.dry", the unit is set aside to cool. Vapors within the unit then condense, to afford from 1 to 2 ml. of final solution within the receiver.